Viral-associated trichodysplasia spinulosa: a case with electron microscopic and molecular detection of the trichodysplasia spinulosa-associated human polyomavirus.

Trichodysplasia spinulosa (TS) is a folliculocentric and clinically papular dermatological disorder occurring in the setting of immunosuppression typically in association with solid organ transplantation or hematolymphoid malignancies. We report the occurrence of TS in a 7-year-old girl with Down syndrome and pre-B-acute lymphoblastic leukemia who was completing chemotherapy at onset. The patient's affected follicles were dilated by an expansion of a dystrophic follicular inner root sheath cell population displaying enlarged trichohyaline cytoplasmic granules and progressing centrally to keratotic and parakeratotic debris, and superficially demonstrating some diminutive hair shaft-like material within the keratotic spicules. Electron microscopic studies of a follicular lesion showed extracellular viral particles suggestive of a polyomavirus within the central follicular keratotic debris. DNA polymerase chain reaction (PCR) and gene sequencing studies, performed on the tissue of the microscopic slide and paraffin block, for the recently identified TS-associated polyomavirus (TSPyV) resulted as positive for TSPyV. PCR for the Merkel cell polyomavirus was negative. To date, this case is unique in representing the first case of TS confirmed by electron microscopy in which a related viral pathogen has been molecularly identified. An additional 19 reported cases classifiable as TS are tabulated and reviewed.

Lipoma arborescens of the hip.

Lipoma arborescens is a rare intra-articular lesion characterized by extensive villous proliferation of the synovial membrane and hyperplasia of subsynovial fat. Although it has been described as arising from traumatic, inflammatory, rheumatologic, developmental, and neoplastic causes, its etiology remains unknown. This article describes in detail--for the first time in the orthopedic literature-a case of lipoma arborescens of the hip. Clinical presentation, histologic and radiographic findings, and treatment of this rare lesion are discussed. Based on clinical, radiologic, and surgical evaluation, differential diagnosis for this lesion should include other conditions that cause synovial thickening, proliferation, and joint effusion--for example, synovial chondromatosis, pigmented villonodular synovitis, synovial hemangiomatosis, and rheumatoid arthritis. Description of this case covers the full radiologic evaluation, including magnetic resonance imaging (MRI), diagnostic pathologic description, and minimum 24-month follow-up. Although lipoma arborescens of the hip is a rare condition, it should be considered in the differential diagnosis of patients with its characteristic clinical prodrome and MRI findings confirming a periarticular fatty mass.